>equation "learning curve = acquired knowledge / elapsed time"

I think you equation has an error in it. Instead of elapsed time it should be the time to some deadline. For example, taking on a new position possessing a lot of complexities and being told to learn as much as you can before the incumbent retires. That is a steep learning curve. The opposite would be if you were elected to the back benches, where all you must master is the art of standing up on occasion as directed by the whip.